Just thirty miles north of Seattle, Washington, at the end of the Strait of Juan de Fuca, sits Whidbey Island, the state's largest island. Whidbey is just a short ferry ride from where I live, in fact, and on a nice day there's not a prettier spot for a quick lighthouse hike and seaside picnic or a bike ride to spot migrating orca and gray whales. But locals here aren't content just to claim that Whidbey Island is picturesque. No, they insist—improbably—that their home is the longest island in the United States. Time to settle this once and for all.

Size matters on Whidbey Island.The "Longest Island" distinction is a surprisingly big deal for Whidbeyites. Local shops sell T-shirts and mugs with the claim, and the history museum hands out newsletters bragging about the length to skeptical out-of-towners. Their main target: New Yorkers, who often arrive under the impression that the aptly named Long Island, in their home state, is the nation's longest.

Long Island is eight times the size and has better iced tea.The irony is easy to see on a map, however. Whidbey Island is only about 35 miles as the crow flies from its northernmost to southernmost points. The island is shaped like a curlicue, however, and curves make it tricky to measure the "length" of a landform. But even if you had to walk from one tip of Whidbey to the other, you could do it in 40 miles or so. By comparison, Long Island—the largest island in the contiguous 48 states—is 118 miles from end to end.

Whidbey Island appeals to a higher court.But Washington State has an answer for the 75-mile difference! Whidbey partisans point out that, in a 1985 Supreme Court decision that settled the offshore boundaries between Rhode Island and New York, the justices decided to treat Long Island as a peninsula, in order to simplify the legal issues involved. Presto: Long Island is a peninsula and Whidbey Island wins by the disqualification.

Short answer: Whidbey is maybe in the top five.The problem, of course, is that Long Island being treated as a peninsula for the legal purposes of one court case doesn't make it into an island geographically. Long Island is surrounded by water on all sides, except for the bridges attaching it to Manhattan, the Bronx, and Staten Island. It's an island. (In 1934, Whidbey was connected by bridge to another island as well—at the gorgeous Deception Pass Bridge, later immortalized in a Mudhoney song.) And even if it we ignore Long Island, Whidbey would still have to contend with Padre Island, a 113-mile-long barrier island off of Corpus Cristi, Texas (which was longer than Long Island before a shipping channel cut it in half in 1957), North Carolina's Hatteras Island, and possibly Isle Royale in Lake Superior.

I love you, Whidbey Island, but you're going to have to settle for "longest Pacific coast island south of Alaska."